Centrifugal refrigerant gas compressor capacity control

ABSTRACT

A capacity control for a refrigerant gas compressor is comprised of a throttle disk in a throttle intake passage leading to a nozzle intake passage extending to the intake portions of a rotatable centrifugal gas impeller and gas flow directing vanes are positioned within the nozzle intake passage to properly direct the gas flow from the throttle disk to the impeller vanes.

[151 3,635,580 [451 Jan. 18, 1972 3,160,] 12 12/1964 Flaton eta1.............................415/147 [54] CENTRIFUGALREFRIGERANTGASCOMPRESSOR CAPACITY CONTROL FOREIGN PATENTS OR APPLICATIONS 736,2076/1943 Germany [72] lnventors: Douglas K. Richardson, Staunton; John G.

Johnson, Waynesboro, both of Va.

727,649 4/1955 GreatBritain.........................4l5/150 [73]Assignee: Westinghouse Electric Corporation, Pittsburgh, Pa. PrimaryExaminer-Henry F. Raduazo Attorney-4 H. Henson and F. E. Blake [22]Filed:

Feb.26,l970

[57] ABSTRACT A capacity control for a refrigerant gas compressor iscomprised of a throttle disk in a throttle in nozzle intake passageextending to rotatable centrifugal gas impeller an are positioned withinthe nozzle i [2]] Appl. No.:

take passage leading to a the intake portions of a d gas flow directingvanes ntake passage to properly direct the gas flow from the throttledisk to the impeller vanes.

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2 Claims, 5 Drawing Figures References Cited Wood........................4l5/l50 CENTRIFIUGAL REFRIGERANT GAS COMPRESSOR CAPACITY CONTROLCROSS REFERENCES TO RELATED PATENT APPLICATIONS A centrifugalrefrigerant gas compressor for which the capacity control of the presentinvention may be particularly suitable is disclosed in the copendingpatent application Ser. No. 14469.

BACKGROUND OF THE INVENTION Recent developments have enabled the use ofcentrifugal refrigerant gas compressors for relatively smallairconditioning machinery for which reciprocating gas compressors havepreviously been considered to be more economically suitable. In order tohave the many advantages of a centrifugal type of gas compressor inthese smaller air-conditioning systems, it is desirable to have asimple, inexpensive and reliable capacity control for varying thecompressed gas output of the centrifugal compressor to meetair-conditioning system requirements without appreciably varying thespeed of the compressor impeller from its most efficient design speed.

PRIOR ART Capacity controls for centrifugal refrigerant gas compressorsas used in air'conditioning systems are disclosed in U.S. Pat. No.3,248,896 to Plaster issued May 4, 1966, U.S. Pat. No. 3,350,897 toPlaster issued Nov. 7, 1967, and US. Pat. No. 3,362,185 to I-Iarnishissued Jan. 9, 1968. The capacity controls as disclosed in the abovepatents are of the movable inlet spin vane-type and are relatively morecomplex than the capacity control of the present invention. Applicantsare unaware of any prior disclosures disclosing a centrifugal gascompressor capacity control of the nature described and claimed herein.

SUMMARY OF THE INVENTION In accordance with the present invention, athrottle intake passage leads through a nozzle intake passage thatextends to the rotatable centrifugal gas compressor impeller. A throttledisk is pivotally mounted with the throttle intake passage and ismovable from a minimum capacity position with the disk positionedtransverse to the gas flow to a maximum capacity position with the diskpositioned in parallel to the gas flow. In order to eliminate a vortexat the impeller inlet, a plurality of flowdirecting vanes are positionedwithin the nozzle intake passage that extends between the throttle diskpassage and the impeller vanes. The throttle disk may be provided withat least one aperture to predetermine the gas flow for the minimumcapacity of the gas compressor. In the preferred form of the invention,a ring piston is concentrically positioned about the outer walls of thethrottle intake passage and is connected by suitable linkage such as abellcrank to translate the reciprocatory movement of the piston topivotal movement of the piston to pivotal movement of the throttle disk.In order to reciprocate the piston, a cylinder is arranged concentric tothe outer walls of the throttle intake passage and surrounding thepiston so that fluid under pressure may be selectively applied to eitherside of the piston to move the piston accordingly.

BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of theinvention will be apparent with reference to the following specificationand drawings in which:

FIG. 1 is a fragmentary sectional view partly in elevation of acentrifugal gas compressor with the capacity control of the inventionand showing the throttle disk in the full capacity position;

FIG. 2 is a view similar to FIG. I but showing only the throttle passageand the intake nozzle passage with the throttle disk in the minimumcapacity position;

FIG. 3 is a fragmentary section on the line lIIIIl of FIG. 2;

FIG. 4 is an even more fragmentary view similar to FIG. 2 but showingthe throttle disk in an intermediate capacity position; and

FIG. 5 is a section on the line V-V of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1 of thedrawings, the centrifugal refrigerant gas compressor is shown to includethe rotatable impeller 10 mounted on the end of the impeller shaft 111for rotation therewith, A gas-collecting scroll 12 is positioned tosurround the impeller 10 and collect through the diffuser structure thecompressed gases issuing; from the compressed gas passages 13 of theimpeller 10. The impeller 10 is also provided with intake gas passages14 that are centrally located and the rotation of the impeller 10 causesthe gas entering the impeller intake passages 14 and passing between theimpeller vanes such as shown at 15, to be discharged under pressure fromthe discharge passages such as shown at 13 around the periphery of theimpeller 10 as is well known to those skilled in the art.

In order to vary the capacity of the centrifugal gas compressor withoutsubstantially changing the speed of the rotation for the impeller 10,this invention provides for a novel arrangement of movable throttle disk20 and a plurality of gas directing vanes such as shown at 20 through23. It should be understood that the invention is not limited to anyparticular number or precise configuration or angle of direction of thegas flow directing vanes 20-23.

It will be noted that the throttle disk 20 is mounted within a throttleintake housing 30 and is pivotal therein from the maximum capacityposition shown in FIG. 1 to the minimum capacity position shown by FIG.2 of the drawings. In order to enable the throttle disk 20 to be somoved within the throttle intake passage 30, the throttle disk 20 issecured to pivotal stub shafts 31 and 32. The stub shaft 31 is connectedby a bellcrank 33 and the stub shaft 32 is connected by a bellcrank 34to respective pins 35 and 36 received in a groove 37 of a reciprocatorypiston 38.

As shown in more detail by FIGS. 2, 4i and 5 of the drawings, the piston38 is a ring piston concentrically mounted around the outer wall 39 ofthe throttle intake passage 30. A cylinder wall 40 is alsoconcentrically mounted around the outer wall 39 of the throttle intakepassage 30 in a manner to enclose the reciprocatory piston 38 and fluidunder pressure is introduced within the cylinder selectively to eitheror both sides of the piston 38 for reciprocating the piston accordinglyin a manner to move or maintain the throttle disk 20 at a desiredposition. The aforementioned US. Pat. Nos. 3,350,897 and 3,362,185disclose various ways for valving fluid under pressure to either or bothsides of a capacity control piston such as the piston 38 as used in thepresent invention. Since the arrangement for supplying fluid underpressure selectively to either or both sides of the piston 38 is not apart of the present invention, and any suitable arrangements well knownto those skilled in the art may be used, the details of such anarrangement have been omitted from the present disclosure.

Referring now to FIGS. 1, 2 and 3 of the drawings, it will be seen thata nozzle intake passage 50 is positioned between the throttle intakepassage 30 and the impeller 10 to converge and direct the gas flow fromthe throttle disk 20 into the intake passages 14 of the centrifugal gascompressor impeller 10. A feature of the invention is the provision ofthe aforementioned gas flow directing vanes such as shown at 2043, todirect the flow of gas coming from the throttle disk 20 to thecentrifugal gas impeller.

Referring again to the drawings, it will be seen that the throttle disk20 is provided with the aperture 25, which, when the throttle disk 20 isin the minimum capacity position shown by FIG. 2 of the drawings,provides a minimum gas flow into the intake nozzle 50 and the gasimpeller. This invention is not limited to the provision of a centrallylocated aperture such as shown at 25 but one or more apertures :may beused in various positions as will be obvious to those skilled in theart.

There has been described an exceedingly simple, inexpensive and reliablecapacity control for a centrifugal refrigerant gas compressor in which asingle valve disk in combination with suitably positioned gas flowdirecting vanes are used to modify the flow of refrigerant gas into thecentrifugal gas compressor impeller and thereby vary its capacity.Various modifications will occur to those skilled in the art.

We claim:

1. A capacity control for a centrifugal refrigerant gas compressorhaving a rotatable impeller with centrally located intake passages andperipherally located compressed gas passages, comprising, a throttleintake passage, a nozzle intake passage extending from said throttleintake passage to the centrally located intake passages of saidimpeller, a throttle disk pivotally mounted in said throttle intakepassage and having at least one aperture for determining the minimumcapacity of said compressor when the throttle disk is in a minimumcapacity position, means to move said disk from a position transverse tothe gas flow for minimum capacity to a position parallel to the gas flowfor full capacity and any position therebetween, and a plurality of gasflow directing and straightening vanes extending within said nozzleintake passage to direct the flow of gas into said impeller afterpassage from said throttle disk.

2. The invention of claim 1 in which the means to move said disk iscomprised of a ring piston concentrically mounted on the outside of saidthrottle intake passage and connected to said disk by means of abellcrank to translate reciprocatory movement of said piston to pivotalmovement of said disk, and means to enclose said piston in a cylinderconcentric with said throttle intake passage for applying a fluid underpressure within said cylinder to either side of said piston forreciprocating the piston in accordance therewith.

1. A capacity control for a centrifugal refrigerant gas compressorhaving a rotatable impeller with centrally located intake passages andperipherally located compressed gas passages, comprising, a throttleintake passage, a nozzle intake passage extending from said throttleintake passage to the centrally located intake passages of saidimpeller, a throttle disk pivotally mounted in said throttle intakepassage and having at least one aperture for determining the minimumcapacity of said compressor when the throttle disk is in a minimumcapacity position, means to move said disk from a position transverse tothe gas flow for minimum capacity to a position parallel to the gas flowfor full capacity and any position therebetween, and a plurality of gasflow directing and straightening vanes extending within said nozzleintake passage to direct the flow of gas into said impeller afterpassage from said throttle disk.
 2. The invention of claim 1 in whichthe means to move said disk is comprised of a ring piston concentricallymounted on the outside of said throttle intake passage and connected tosaid disk by means of a bellcrank to translate reciprocatory movement ofsaid piston to pivotal movement of said disk, and means to enclose saidpiston in a cylinder concentric with said throttle intake passage forapplying a fluid under pressure within said cylinder to either side ofsaid piston for reciprocating the piston in accordance therewith.